Vinyl coated and laminated backlit signs and awnings are in wide use throughout the world. Fabrics that are used as the strength member in such applications should have exceptional geometry, the ability to withstand the rigors of further processing without distortion, and yet stable enough for use in subsequent high speed manufacturing processing.
Typically, backlit signs and awnings are constructed of a translucent sheet or panel that is stretched about a metal framework, and have a light source placed on the side opposite the side being viewed. By selectively printing opaque regions on the fabric panel, words or graphics may be formed by the translucent portions of the fabric panel. The overall effect is a lighted sign that is relatively durable, and which may be viewed during the day and at night.
The material that is commonly used to form awnings is a PVC (polyvinylchloride) film or a related PVC-based material; e.g., PVC films laminated onto knitted polyester scrims (reinforcement fabric). PVC has limited durability, tear resistance, and integrity, particularly after prolonged exposure to the outside elements and UV radiation. Consequently, it has been necessary to provide a fabric substrate or scrim for the plastisols or films to give the awning fabric sufficient strength, durability, and integrity.
Attempts have been made to utilize a scrim or woven mesh panel for constructing backlit signs and awnings. However, the presence of a scrim has been found to significantly compromise the aesthetics of the backlit awning sign. In this regard, the scrim of conventional awning fabrics tends to absorb substantially all of the incident light, making the outline of the scrim pattern highly visible to the viewer. In an attempt to mask the mesh outline, manufacturers reduced the overall area of the awning fabric covered by the scrim in order to obtain more uniform transmission of light through the fabric. This was accomplished by using low denier yarns to form the scrim and/or enlarging the interstices defined within the scrim. The result was a proportionate reduction in the durability and strength of the fabric.
To overcome these disadvantages, the inventor of the present invention previously developed a backlit and awning fabric comprising a woven scrim that was treated with an optical brightener (see U.S. Application Ser. No 08/594,984). A translucent coating or PVC plastisol was cast onto release paper and then fused together by heat in a commercial oven. A second PVC plastisol coating was cast on top of the fused PVC-release paper on which the woven scrim was laminated. These combined layers were smoothed with finishing rollers to produce a white fabric. Lastly, ink was printed on to the fabric.
While this backlit and awning fabric is superior over existing fabrics with similar applications, there remains a need to develop new and more efficient processes for applying the ink layer onto fabric to improve the visual standards for quality backlit signs. The application of the PVC plastisol to the fabric prior to the inking operation is inefficient and results in excess waste of vinyl coated fabric when the ink application is defective or in error. Further, when wet ink is applied to the PVC layer, the ink tends to diffuse into the PVC leaving a somewhat fuzzy pattern edge when the ink is later eradicated to produce the selected pattern. Thus, there is a need to produce an awning fabric which produces a higher resolution image following eradication.